Unloader and cut-off valve



@Fume '3 1924.

B. s. AIKMAN UNLOADER AND CUT-OFF VALVE Filed ngrch 3o N\ mmf Patentedalune 3, 1924.

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srArasfiPATEN `:BURTON S. AIKMAN, 0F MILWAUKEE, WISCONSIN, ASSIGNOR T0NATIONAL BRAKE & ELECTRIC COMPANY, 0F MILWAUKEE, WISCONSIN, .A CORPORATI0F WISCONSIN.

UNLOADEB AND CUT-OFF VALVE.

Application tiled March 30, 1921. Serial No. 456,843.v

To all whom it may concern.' v

Be it known that I, BURTON S. AIKMAN, a

.citizen ofthe United States, residing at Mil- Milwaukee and unloadingthe compressor upon starting, and

for cutting olf the connection between the storage tank and thecompressor so that leakage of air will be prevented.

I have observed that in air compressors where the air is stored in astorage tank which is periodically depleted, the starting of thecompressor is, (in the smaller sizes), made difficult 'by the leakage ofair past the check-valve into the discharge pipe of the compressor. 0nlarger installations it is customary to employ a device for holding theintake valve of the compressor away from seat, so that the motorV can bebrought to speed before the intake valve is permitted to seat, so thatthe motor has suiiicient ower to carry the load. In smaller`installations, it is the practice to employ merely a check valve betweenthe storage tank and the compres-- sor, and to depend upon the leakagefor evacnation of the compressor discharge pipe, so that the compressormay start without load. If a bleeder port in the discharge pipe of thecompressor 1s provided, there is during 'compressing of the air a veryconsiderable waste of power due tothe leakage of" compressed air fromsaid bleeder port. If no bleeder port is provided, the discharge pipe ofthe compressor will not be properly Aevacuated. This is due to the factthat a check valve in the discharge line of the compressor will not staytight very long. Due to the constant pounding of the valve upon itsseat, it. quickly reaches a oint where the valve and the seat do not fileakage is the result. Various attemptshave been made to cure thisdifiiculty, but. it api pears to be inherent in the use of a check valvethat the valve and the seat will pound and destroy the lit between theseparts.

It is the primary object of my invention to obviate the necessity for acheck valve by Y t closely, and serious providing a cut-0H valve whichis actuated when the compressor is stopp'ed to cut olf the connectionbetween the compressor and the storage tank. This cut off valve operatesboth as a. stop and waste valve to permit the contents of the dischargepipe between said valve andA the compressor to escape to atmosphere, sothat the compressor is unloaded until it isl again put into operation,even though the periods of time between successive operations of thecompressor are very brief.

I combine the pressure control switch -which governs the cutting in ofthe driving motor with'this cut off and unloading valve, so that whenthe pressure in the reservoir has reached a predetermined value, themotor will be stopped, the cut olf valve will be closed, and thecompressor will be unloaded for the next operation.

In order to acquaint those skilled in the art with the manner ofconstructing and operating my invention, I will now describe aparticular embodiment of the same in connection with the accompanyingdrawings, in which:

Figure l represents, partly in section, and partly diagrammatically, anair compressing system embodying my invention; and,

Figure 2 is a plan view of the governor or controller.

The system illustrated includes the conipressor l, the storage tank 42and the control device 3. The compressor 1 is driven b an electric motor2, toy which it is suitably elted, or otherwise connected., as indicatedat 4. The circuit of the motor 2 is controlled by a pressure-controlledswitch 5, which may This governor is modified in order to operate thecut off and unloading valve, as will be de- 0o scribed later. Thegovernor 5 comprises a stationary contact. 6, and a movable contact 7which are connected in the circuit 48 of the motor 2.

The movable contact 7 is controlled by a 05 pressure sensitive elementcomprisin the diaphragm 8, which diaphragm 1s subjected on its lowerside'to the pressure in the cylinder 9, this cylinder being incommunication with the storage tank 42 through a pipe .10.

A movable spring pressed piston 11 rests upon the top ofthe diaphragm,this piston being held in its downward position by a.

spring 12, which tends to oppose the pressure 'of the compressed air on'the lower side of the diaphragm 8.. The piston l1 is B 15, which ispressed downwardly by the s ring 12 to oppose the movement of theaphragm 8. The collar 15 has a groove which embraces a cross pin or rod16 connected in the sides of the levers 18, which l5 levers are pinnedupon a common shaft or pivot 19 at the rear of the controller orgovernor. The forward end of the levers 18 are connected to the shortarms 21 at the pivot 20, the short arms 21 bearing a flat spring 22,upon the outer end of which is the contact 7. This contact is connectedto one side of the circuit 8. The outer side of the circuit is connectedto the stationary contact 6. A pair of springs 24, 25 shown in Figure 2,connect the pins 19 and 23, and tend to cause the arms 18 and 21 whichform a toggle mechanism, to collapse on one side or the other ascontrolled by the upward or downward movement of the collar 15. Uponupward movement of the collar 15, the pin 16 is raised until the contact7 engages the stationary contact 6, whereupon the toggle will be brokenin the opposite direction and the spring 24 will 33 cause the toggle tocollapse suddenly, whereupon the contact 7 .is separated from thecontact 6 with a quick snap action. Upon the reverse operation, namely,lowering of the collar 15, the pivot 2O will be brought below the lineof center of the pins 19 and 23 whereupon the springs 24 will lift thecontact 7 upwardly, closing it against theA contact 6.

The compressor 1 and the tank 42 are connectedV through pipes 25 and 26,which are separated by a valve body 27. This valve body 27 serving as asuitable support for the controller 5. The valve body 27 contains apassageway therethrough, which is obstructed by the walls 28 and 29,walt 28 having a passageway 30 therethrough, normally obstructed by aball check valve 31, this check valve 31 being guided in a tubularextension 32 of a pop valve 33, which lies immediately above it. Thewall 29 contains a passageway 34, which pas sageway is controlled by thecut oil valve 35. The valve 35 has a stem 36, which is fluted to permitair to pass the same. D as will bel described more at length later. Thisstem passes through a cover plate 37, which is clamped over an openingof the side Wall of the valve -body 27. A spring 38 tends to raise thevalve 35 against a @-seat 39 which *is formed in the cover plate 37. Abutton of insulating material lies above the stem 36 and below thecontact 7, in such osition that when the contact 7 is lowered the button40 will be pressed down and will engage the top ot' the stem-36, openingthe valve 35 away from The air which is then contained in that part ofthe system delined by the wall 29 and the compressor 1 is rapidlydischarged to atmosphere, whereby the compressor is unloaded for thenext start. The pop valve 33 is seated over the small check valve 31, inorder to form a guide for the same, but it is to be understood that ascrew cap might be employed for the same purpose.

The operation of the device is as follows: Assuming that the pressure inthe tank 42 is depleted to such anextent that. the spring 12 forces thecollar l5 downwardly, causing the toggle arms 18 and 21 to throw thecontact 7 upwardly against the stationary contact 6: Thereupon, thecircuit for the y motor 2 will be closed. The spring 38 raises the valve35 against its seat 39, but pressure from the tank 42 does not .enterthe discharge pipe 25 of the compressor, because the small check valve3l prevents retrograde movement of the same. Even if the small valve 31is not tight against its seat, it will prevent the sudden rush of coni-vpressed air back into the discharge pipe 25, and will-permit thecompressor 1 to be started-before it is fully loaded. The pipe 25between the 4check valve 3 and compressor l has sulicient capacity topermit the compressor to make about a half-dozen strokes before thepressure therein is raised to the minimum tank pressure. This per-- mitsthe compressor, therefore, to take up its load gradually, and in fact,to start Without being overloaded.

As soon as the pressure in the pipe '25 becomes great enough, the checkvalve 3l will be forced away from its seat with each stroke of thecompressor l, and air will be discharged into the storage tank 42. Whilethe port 34 is relatively small, it does not serve as a restriction ofany importance. This is particularly true because of the capacity ofpipe 25.

As soon as the tank 42 is charged to the proper pressure, the diaphragm8 will be forced upwardly, whereupon the toggle, arms 18 and 21 will bepressed upwardly, and the spring 24 will spring the contact 7downwardly, opening the circuit 48, and at the same time moving thevalve 35 away from its seat 39, and moving it against its seat over theport 34. This places the discharge pipe 25 and space Vbetween 'the walls29 and 28 in communication with the atmosphere through the opening aboutthe stem 36. Air is free to move from the discharge pipe 25 past thevalve 31, because vented, or at least is greatly hindered by the side ofthe check valve,

valve 31 tending to seat in the reverse direction.

The cut-off and unloading valve 35 may be formed as tWo separate valvebodies without departingfrom my invention. The fundamental requirementis that if the cutoff port is closed, the relief port should be open,and vice versa. It is immaterial whether the check valve is` employed inthe same valve case, or in a separate case, the'fundamental requirementbeing that the check valve lie on the compressor side of the cut offvalve. The relief port may be on either but it must communicate with thecompressor side of the cut-off valve.

The location of pop valve 33 on the compressor side of the cut 0H valve35 is 1mportant.

Quite often when the pop valve is operated either manually orautomatically, it will not seat absolutely tight, with the result thatleakage occurs. The purpose of a pop valve is to prevent the compressorfrom raising the pressure of the tank to a dangerous point. In otherwords, a pop valve is useful only when the compressor is operating,since the pressure is created by the compressor. Consequently, I havedisposed the pop valve 33 on the compressor side of the -out oii' valve,where any leakage of this pop valve will occur only during operation ofthe compressor. Usually the ratio of time between the running of thecompressor and the standing of the tank 42 under pressure i-s verysmall. Consequently,

Y a leaky pop valve located in the present situation will cause aminimum of loss. ItV is obvious that the pop valve may be locatedanywhere on the compressor side of the cutofi' valve 35, but I prefer toplace it above the ball check valve 31, so that it may be mounted uponthe same base which supports the switch and cut 0H valve.

I claim:

1. In combination a Huid compressor having the usual valves, a pressuretank charged by the same, a discharge pipe from the compressor to thetank, a pressure controlled cut-oif and unloading valve in the dischargepipe between the compressor and the tank and a check valve between saidfirst valve and the compressor for preventing .the pressure from thetank from being imposed upon the compressor when the cut-off valve isopened.

2. In combination a compressor having t0 the usual inlet and dischargecheck valves,

sageway, said walls having ports thereloading the compressor,

Ahaving a valve. face for controlling said last named port.

3. In combination a tank, a compressor, a discharge pipe between thetank and the compressor, a stop and waste valve in said pipe, and acheck valve also connected in said pipebetween said first valve and thecompressor the discharge pipe between the compressorv and the checkvalve being adapted to receive the air delivered by several strokes ofthe compressor before the pressure .therein rises to .tank pressure.

4. In combination a storage tank, a compressor, a discharge pipe betweenthe tank and the compressor, a stop and waste valve in said pipe, andpressure controlled means subject to the pressure in thetank foroperating said stop and waste valve said valve having snap actuatingmeans for opening the valve at a predetermined maximum pressure and forclosing the valve at a predetermined minimum pressure.

5. In combination a storage tank, a compressor, a motor for thecompressor, a control switch for the motor, tween the compressor and thetank, and a pressure sensitive element for opening the switch andclosing the cut-off valve when a predetermined pressure in the tank isreached.

6. In combination a storage tank, a compressor, a motor for thecompressor, a control switch for the motor, a connecting pipe betweenthe compressor and tank, a stop an waste valve in said pipe for shuttingoff the tank from the compressor and for unand a pressure sensitiveelement for opening the switch and closing thefcut-oti1 valve when apredetermined pressure in the tank is reached.

7. In combination a storage tank, a compressor, a pipe connectingthecompressor and the tank, va transverse wall in a portion of said pipe, aport therethrough, a waste port in alignment with said first port, and adouble acting poppet valve controlling said first port for'cutting olfcommunication between the tank and the compressor, and for controllingsaid second port to unload the compressor, said poppet valve hea cut-oifvalve being actuated upon the attainment ofa pref determined pressure insaid storage tank.

8. In a valve of the character described,

a cut-off port, a Waste port. a poppet valve adapted to control saidport, a pressure controlled diaphragm, a pair of tog le larms controlledby said diaphragm, and a snap spring for said toggle arms, said togglearms-controlling the operation of said poppet lvalve. y l

9; In combination a compressor, astorage tank, a connection between saidcompressor and said tank, a pressure act-uated cut-off valve in theconnectionresponsive to a predetermined pressure in the tank forclo'sing oit the connection between the compressor and the tank, and apop valve located -on the compressor sideot said cutoffv valve.

10. In combination, a compressor, a storage tank therefor, a dischargepipe for the compressor, a cut-off and unloading vvalve in the dischargepipe between the compressor and the tank` a check valve between saidfirst valve and the compressor,'and means for stopping'the compressorwhen the cut-oit valve is operated.

ll. In combination, a tank, a compressor, a discharge pipe from thecompressor to the tank, a motor, a controller having apressure-sensitive element adapted to act upon a predetermined maximum,pressure and upon a predetermined minimum pressure in the tank to stopand start the motor, and a cut-off valve located in said pipe adjacentthe tank, said valve being controlled by said pressure-sensitiveelement.

152.v In combination, a tank, a compressor, a dischargepipe from thecompressor to the tank, a motor, a controller having apressure-sensitive element adjusted to act upon a predetermined -maximumpressure and upon a -predetermined minimum pressure in the tank to stopand start the motor, a

control switch for the motor governed by said element, and a cut-off andunloading valve located in said pipe adjacent the tank, said valve beingalso controlled by said element.

13. In combination, a tank, a compressor, a discharge pipe fromthecompressor to the tank, a motor, a controller having apressure-sensitive element, a cut-oli` valve located in said pipeadjacent the tank,said valve being controlled by said element, and meansactuated together with said cut-oil valve for stopping the motor.

14. In combination, a tank, a compressor connected to the tank by a pipewhich requlres several strokes of the compressor to fill it topredetermined minimum pressure, a check valve and a pressure-controlledcutoff valve located in saidpipe adjacent the tank, and a po valveconnected to said pipe between sai cut-01T valve and the compressor,said'check valve lying on the compressor side of the cut-oil valve.

15. In a controller andv cut-oil' valve,'a pressure-operated diaphragm,a switch arm bearing a movable contact, ast'ationary contact above saidmovable contact, a valveoperating stem below said movable contact, and avalve actuated by depression of the stem, said stem being. depressed bythe naeeio 'downward movement of said arm to open sitive diaphragmmounted on said diaphrag'm chamber, a switch adapted to be actuated bysaid diaphragm, a substantially horizontal wall on the interior of saidvalve casing, said wall having a port therethrough,

a cut-oil' and unloading valve passing through a wall of the valvecasing controlling said port, said valve having a stem adapted to bedepressed by said switch when 'said switch is opened, a secondhorizontal wall having a valve port therethrough and a check valvecovering said valve port.

17. A cut-oli'l and check valve comprising a valve casing, a diaphragmchamber mounted on the top of said casing, a pressure-sensitivediaphragm mounted on said diaphragm chamber, a switch adapted to beactuated by said diaphragm, a substantially horizontal wall on theinterior of said valve casing, said wall having a port therethrough, acut-oil and unloading valve passing through a wall of the valve casingcontrolling said port, said valve having a stem adapted to be depressedby said switch when said switch is opened, a second horizontal wallhaving a valve port therethrough and a check valve covering said valveport, an opening through the top sideY of the valve casing substantiallyin line with said last named valve port and a pop valve having a stemthreaded in i said opening over said check valve.

18. In combination, a compressor, a tank therefor, an automaticallycontrolled switch for stopping and starting the compressor in accordancewith the pressure in the tank, a discharge pipe for the compressor, acuto and unloadlng valve in the discharge between the compressor and thetank, and a check valve between said first valve and the compressor.

19. In combination a compressor, a storage tank therefor, a dischargepipe for the compressor, a cut-off and unloading valve in the dischar epipe between the compressor and the tan, and a check valve independentof said compressor between the first named valve and the compressor toprovide a relatively small storage space at substantially atmosphericv`pressure when the compressor is started so the compressor nd not startunder load.

20. .In combination, a compressor having the usual inlet and dischargecheck valves, a storage tank, a pi e connectin said compressor and saidta and inclu ing a combined unloadin and cut-oil valve for thecompressor, sai valve having a passageway therethrough, a cut-0E valveport forming partof the passageway, a check valve port @Asume a forminga Vpart of said passageway and lycontrolled means governed .by thepressure in in on the compressor side of the cut-off the storage tankfor operating said eut-oil' va ve, a check Valve for said latter port, avalve. l l0 g relief port communicating with said pasf In Witnesswhereof, hereunto subscribe 5 saJ eway on the compressor side of theeutmy name this 25th day of March, A. D. 1921. og valve, and valve meansfor governing said rst and. seid last port, and pressure BURTON yS. AANL

